Multi-piston variable stroke pump



Dec. 14, 1965 G. N. THRESHER MULTI-PISTON VARIABLE STROKE PUMP 4 Sheets-Sheet 1 Filed June 14, 1963 FIG. 2

INVENTOR. GRIFFITH N. THRESHER ATTORNEVS Dec. 14, 1965 N. THRESHER MULTI-PISTON VARIABLE STROKE PUMP 4 Sheets-Sheet 2 Filed June 14, 1963 GRIFFITH N. THRESHER Dec. 14, 1965 N. THRESHER 3,223,042

MULTI-PISTON VARIABLE STROKE PUMP Filed June 14, 1965 4 Sheets-Sheet 5 I NTOR. GRIFFITH N. RESHER ATTORNEYS Dec. 14, 1965 G. N. THRESHER MULTI-PISTON VARIABLE STROKE PUMP 4 Sheets-Sheet 4 Filed June 14, 19 63 INVENTOR. GRIFFITH N. THRESHER 4.4

ATTORNEYS United States Patent 3,223,042 MULTI-PISTON VARIABLE STROKE PUMP Griflith N. Thresher, Tulsa, Okla., assignor to Frank Wheatley Corporation, Tulsa, Okla, a corporation of Oklahoma Filed June 14, 1963, Ser. No. 288,025 4 Claims. (Cl. 10338) This invention relates to a multi-piston variable stroke pump. More particularly, the invention relates to a pump including means whereby the length of stroke of the pistons of the pump can be varied. Still more particularly, the invention relates to the power end portion of a multi-piston pump of the wobble plate type including means whereby the length of stroke applied to the pistons may be varied quickly and easily by means external of the pump and by means not requiring the pump to be disconnected or disassembled in any way.

Industrial applications frequently require pumps to deliver varying volumes of fluid. Most positive displacement pumps are of the type wherein the speed or r.p.m. of the pump is directly related to the rpm. of the prime mover. The only method of varying the volumetric displacement of such pumps is by varying the speed of the prime mover. Such a method of variable volumetirc displacement is not completely acceptable. Variable speed electric motors for instance are expensive and their application is limited. The basic problem with varying the output of a positive displacement pump by varying the speed of rotation of the pump is that most machinery, especially prime movers, is designed for a given range, usually a very narrow range, of speed of rotation for best efficient and longest life. In any event, for these and other reasons well known to men in all types of industry, it is desirable to provide a positive displacement pump having means for easily varying the stroke of the pump.

Others in the past have provided variable stroke pumps but every known type of variable stroke pump presently available is limited in application due to their complexity and high expense. All of the known types of variable stroke pumps utilize complicated arrangements as means of achieving variable volume output with the result that the costs of such pumps limit their use to specialized applications. The complexity and expense of known types of pumps are particularly detrimental factors in pumps of large capacities and pressures.

It is therefore an object of this invention to provide a multi-piston variable stroke pump which is extremely simple in design and construction, and which has advantages and features superior to other known types of multipiston pumps.

This and other objects and a better understanding of the invention may be had by referring to the following description and claims taken in conjunction with the attached drawings, in which:

FIGURE 1 is an isometric external view of a pump embodying the novel variable stroke provisions of this invention.

FIGURE 2 is a cross-sectional view taken along the line 22 of FIGURE 1 showing the internal arrangement of the pump of FIGURE 1.

FIGURE 3 is an enlarged cross-sectional view of the power end portion of the pump in FIGURE 2.

3,223,042 Patented Dec. 14, 1965 'ice FIGURE 4 is a cross-sectional view taken along the line 4-4 of FIGURE 3.

FIGURE 5 is a cross-sectional view taken along the line 55 of FIGURE 3.

FIGURE 6 is an end view taken along the line 66 of FIGURE 3.

FIGURE 7 is a view of a segmented portion of the power end of the pump showing the pump arranged for minimum stroke length, the segment taken in the area indicated on FIGURE 3.

FIGURE 8 is a cross-sectional view equivalent to the cross-sectional view of FIGURE 4 showing an alternate embodiment of a means of mounting the rearward wobble plate of the pump.

This invention may be described as a multi-piston variable stroke pump. More particularly, but not by way of limitation, the invention may be described as a multipiston variable stroke pump power end comprising a housing, a drive shaft rotatably supported in said housing and having the rearward end thereof extending from said housing, a multiplicity of push rods slidably supported in said housing adjacent the forward end of said drive shaft, each of said push rods supported parallel the axis of said drive shaft and each displaced an equal distance therefrom, a forward Wobble plate supported on said drive shaft, said forward wobble plate having engagement at the forward base thereof with the rearward end of each of said push rods, said forward wobble plate free to wobble on said drive shaft, a rearward wobble plate supported about said shaft, the forward face thereof in bearing engagement with the rearward face of said forward wobble plate, the rearward face of said rearward wobble plate being formed at an angle relative to the forward face thereof, a tubular wobble plate adjust member rotatably and axially supported about said shaft, said wobble plate adjust member having a flat forward face thereof inclined at an angle to the axis of said shaft, said forward plate thereof in frictional engagement with said rearward wobble plate, said wobble plate adjust member having a portion thereof extending co-axially of said shaft and exteriorly of said housing, bearing means rotatably supporting said wobble plate adjust member to said housing, and means externally of said housing of adjustably securing said wobble plate adjust member to said shaft.

Referring now to the drawings and first to FIGURE 1, a multi-cylinder pump is shown in exterior view and indicated by the numeral 10. It should be understood that the pump 10, including the more detailed internal views to be subsequently discussed, is shown merely by way of example of an embodiment of the principles of this invention and the invention may be applied to a wide variety of multi-cylinder pumps to obtain variable stroke characteristics.

Power is applied to the pump 10 by a shaft 12 which extends rearwardly of the pump for connection to a prime mover (not shown). The pump 10 may be generally divided into two basic portions, the first portion being the power end 14 by which power is received within the pump by means of shaft 12 and converted for actuation of the pistons in a manner to be described subsequently. Fluid is received into the pump through the fluid inlet opening 16 and passes out of the pump through a downwardly extending outlet port 18. The second portion of the pump, including the pistons, cylinders and valves, is generally termed the fluid end and is indicated by the numeral 20.

In FIGURES 2 through 8 the base on which the pump 10 would be supported is not shown for purposes of simplicity.

Referring now to FIGURE 2, the pump of FIGURE 1 is shown in cross-section. A multiplicity of push rods 22 are mounted parallel to the axis of shaft 12 and grouped at equal distances about the forward end thereof. Push rods 22 connect to and actuate pistons 24. Fluid enters the pump through inlet opening 16 and by means of fluid passages 26 flows into the cylinders. The fluid is forced outwardly through outlet fluid passages 28 which communicate with outlet port 18.

The fluid end portion of the pump is not shown nor described in detail as such is not a portion of this invention. As has been previously indicated, the principles of this invention may be applied to a pump design having a wide variety of pump fluid ends. For a more specific description of a pump fluid end applicable to the pump power end of this invention see co-pending application Serial No. 263,473 entitled, A Valve System for a Reciprocating Pump, filed March 7, 1963.

Referring now to FIGURE 3 the details of the variable stroke provisions of this invention are best shown. The pump power end 14 is shown in enlarged cross-sectional view. The pump power end is provided with a housing 30 in which the working portions of the pump are enclosed. A rearward push rod support plate 32 reciprocately supports the push rods 22 which connect with the pistons 24 of the pump. Push rod guides 34 are provided within which the push rods 22 reciprocate. The portion of the pump to the right of the push rod support plate 32 is described in one embodiment in the above mentioned co-pending application and therefore further description will not be incorporated herein.

Supported about shaft 12 is a forward wobble plate 36 having a forward surface 38 and a rearward surface 40. The forward surface 38 bears against the ends of push rods 22. The forward surface 38 and rearward surface 40 of forward wobble plate 36 are parallel to each other. The bearing 42 is provided by which the forward wobble plate 36 is free to wobble relative to the shaft.

Supported about shaft 12 and rearwardly of the forward wobble plate 36 is a rearward wobble plate 44 having a forward surface 46 and a rearward surface 48. The rearward surface 48 is disposed at an angle relative to the forward surface 46. A hearing 50 is provided between the forward wobble plate 36 and the rearward wobble plate 44.

The forward wobble plate 36 is supported by hearing 42 to wobble on shaft 12. The frictional engagement of the forward face 38 of the forward wobble plate 36 against the ends of push rods 22 maintains forward wobble plate 36 in a non-rotatable position. Although the forward wobble plate 36 is otherwise free to rotate about shaft 12 any rotation would be against the friction imposed by push rods 22 and will therefore be incidental. The rearward wobble plate 44 is rotatably aflixed to shaft 12, in a manner to be described subsequently, and rotates with it. The bearing 50 thereby provides a relative rotation of rearward wobble plate 44 to forward wobble plate 36.

Supported about shaft 12 is a tubular wobble plate adjust member 52 having a forward face 54. The forward face 54 of the wobble plate adjust member 52 frictionally engages the rearward face 48 of rearward wobble plate 44. A rearward main bearing 56 supports the wobble plate adjust member 52 relative to housing 30.

A rearward tubular portion 58 of the wobble plate adjust member 52 extends coaxially of the shaft 12 and rearwardly beyond the confines of housing 30. The tubular portion 58 of the wobble plate adjust member 52 is adjustably secured to shaft 12. One manner of accomshaft.

plishing such adjustable securement includes the provision of a tubular adjust keeper member 60 coaxially positioned about the shaft 12 and secured to shaft 12 by means of a key 62. Bolts 64 extend through a flange portion 66 of the adjust keeper member 60 to securely afiix the adjust keeper member 60 to the tubular extension 58 of the wobble plate adjust member 52. By removal of bolts 64 wobble plate adjust member 52 may be rotated relative to shaft 12 and secured in a new position by replacing the bolt 64 in the adjust keeper member 60.

Fluid packing 68 in seal plate 70 is held in place with bolts 72 to prevent leakage of fluid past the bearing 62 and out of the pump.

One method of securing the components supported by bearing 56 in the pump includes the provision of a removable flange 74.

An adjust member bearing 76 is provided between the forward portion of the wobble plate adjust member 52 and shaft 12 to provide means whereby the wobble plate adjust member 52 may be easily rotated relative to the It should be understood however that in operation wobble plate adjust member 52 rotates with the shaft 12 and there will be no relative movement of the wobble plate adjust member 52 to shaft 12 except when the stroke of the pump is being varied in a manner to be described subsequently.

A forward bearing 78 in the push rod support plate 32 supports the forward end of shaft 12 and acts in thrust relationship relative to the rearward main bearing 56. A lubricating extension 80 of shaft 12 may be provided whereby lubricant is forced through openings drilled in the shaft to the bearings of the pump.

Referring to FIGURE 6, an end view of the pump is shown with some portions in cross-section, to illustrate means whereby key 62 is utilized to affix the adjust keeper member 60 to shaft 12. As was previously described, by removal of bolts 64 the wobble plate adjust member 52 (not seen in FIGURE 6) may be rotated relative to shaft 12 for varying the stroke of the pump.

FIGURE 5 is a cross-sectional view showing the arrangement of the pump and push rods 24 around the shaft 12. Although the invention may be utilized with a variety of different pump end configurations, as has been previously set forth, the embodiment shown is of 1 pump having seven pistons. Springs 81 bearing against spring retainers 81A (see FIGURE 3) serve to bias the piston rods 22 rearwardly against wobble plate 36.

As was previously indicated, the rearward wobble plate 44 is mounted about shaft 12 in amanner so that it rotates with shaft 12 but is pivotal relative to shaft 12 for purposes of adjusting the stroke of the pump. The arrangement of the rearward wobble plate 44 is best shown in FIGURE 4. In this embodiment wobble plate 44 is composed of two semi-spherical portions indicated by numerals 44A and 44B. Opposing openings 82 are provided in each semi-spherical portion 44A and 44B with the openings 82 in portion 44B threaded so that by means of socket head cap screws 84 the two halves 44A and 44B are supported about the shaft 12. Shaft 12 is provided with a longitudinal slot 86 in the area wherein the rearward wobble plate 44 is supported. In the embodiment shown in FIGURE 4 the semi-spherical portions 44A and 44B are each provided with a centrally extending integral projection portion 88 which extend within the slot 86. Thus, the rearward wobble plate 44 as assembled is rotatably secured to shaft 12 but nevertheless may be displaced relative to a plane perpendicular to a longitudinal axis of shaft 12.

FIGURE 8 is an alternate embodiment of a-rearward wobble plate 44, shown also in cross section. In this embodiment the plate 44 is a solid member, having an opening 90 therein through which shaft 12 is received. As previously described, shaft 12 is provided with a longitudinal slot opening 86 which receives a solid shaft 92. The shaft 92 extends in openings 94 provided in the plate 44 in a plane nominally perpendicular to the axis of the plate 44 and shaft 12. The embodiments of the rearward wobble plate 44 as set forth in FIGURE 4 and FIGURE 8 are exemplary and other methods will be suggested of mounting the rearward wobble plate about the shaft in a manner to provide for relative pivotation of the plate to the shaft and at the same time providing positive means of insuring rotation of the wobble plate with the shaft.

OPERATION Referring first to FIGURE 3, when rotary energy is applied to shaft 12, the rearward wobble plate 44 rotates. By the relative position of the rearward face 48 of rearward wobble plate 44 and with the forward face 54 of the wobble plate adjust member 52, the forward face 46 of the rearward wobble plate is set at an angle relative to the shaft 12. As the shaft and therefore the rearward wobble plate 44 rotate this angular displacement is communicated by hearing 50 to cause a non-rotating wobble in forward wobble plate 36. This action is transmitted to push rods 22.

It can be seen that the face 54 of the wobble plate adjust member 52 is in frictional engagement with the rearward face 48 of rearward wobble plate 44 to insure rotation of the rearward wobble plate adjust member with the shaft 12. To further insure no slippage of the rearward wobble plate 44 the provision of the projecting portions 88 in the slot 86 of the shaft 12 prevent the possibility of rotation relative to the shaft. In the same manner, the alternate embodiment of FIGURE 8 will prevent such rotation.

When it is desired to change the stroke applied to push rods 22, bolts 64 are removed from the adjust keeper member 60. Shaft 12 may then be held in a fixed position and the wobble plate adjust member 52 rotated relative to the shaft by means of the rearwardly extending tubular portion 58. For convenience, spanner wrench openings 96 may be provided in the exterior peripheries of the flange portion 58 of the wobble plate adjust member 52 and flange portion 66 of the adjust keeper member 60. The wobble plate adjust member 52 may be rotated a few degrees to secure a new alignment of threaded openings so that bolt 64 may be reinserted. When the wobble plate adjust member 52 is rotated relative to shaft 12 frictional movement takes place between the forward face 54 of the wobble plate adjust member 52 and the rearward face 48 of the rearward wobble plate 44. This is the only time frictional rotation relative to these two components is experienced and likewise, bearing 76 provides rotation of the wobble plate adjust member 52 relative to shaft 12 during such adjustment.

Due to the angular displacement of the forward face 54 of the wobble plate adjust member 52 and the rearward face 48 of the rearward wobble plate 44 rotation of the movement of these two faces changes the total angular displacement of the forward face 46 of the rearward wobble plate 44 relative to a plane drawn perpendicular to the axis of shaft 12. As shown in the segmented view of FIGURE 7, it is possible to provide anarrangement whereby the forward face 46 of the rearward wobble plate 44 may be in a plane perpendicular to the axis of shaft 12. If this is attained rotation of shaft 12 will produce no wobbling effect in the forward wobble plate 36 and therefore no lateral displacement of the push rods 22. This, of course, would not be a desirable design in a working pump but is merely illustrated to show that stroke adjustment may be obtained with the maximum stroke suggested in FIGURE 3 to zero stroke as shown in FIGURE 7.

It can be seen that varying the stroke according to the principles of this invent-ion is accomplished very easily, simple and straightforwardly. While the removal of bolts 64 is required there is no disassembly of the pump itself.

All of the elements necessary for a wide range of stroke changes extend exteriorly of the pump.

Although the invention has been described with a certain degree of particularity it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope.

What is claimed:

1. A multi-piston variable stroke pump power end comprising in combination:

a housing;

a drive shaft rotatably supported in said housing and having the rearward end thereof extending from said housing;

a multiplicity of push rods slideably supported in said housing adjacent the forward end of said drive shaft, each of said push rods supported parallel the axis of said drive shaft and each displaced an equal distance therefrom;

a forward wobble plate supported on said drive shaft, said forward wobble plate having engagement at the forward face thereof with the rearward end of each of said push rods, said forward wobble plate free to wobble on said drive shaft;

a rearward wobble plate supported about said shaft, the forward face thereof in bearing engagement with the rearward face of said forward wobble plate, the rearward face of said rearward wobble plate being formed at an angle relative to the forward face thereof;

a tubular wobble plate adjust member rotatably and axially supported about said shaft, said wobble plate adjust member having a flat forward face thereof inclined at an angle to the axis of said shaft, said forward face thereof in frictional engagement with said rearward face of said rearward wobble plate, said wobble plate adjust member having a portion thereof extending coaxially of said shaft and exteriorally of said housing;

bearing means rotatably supporting said wobble plate adjust member to said housing; and

means externally of said housing of adjustably securing said wobble plate adjust member to said shaft.

2. A multi-piston variable stroke pump power end according to claim 1 including means of pivotally and non-rotatably supporting said rearward wobble plate to said drive shaft.

3. A multi-piston variable stroke pump power end according to claim 2 wherein said drive shaft has an elongated slot extending therethrough at the area thereof receiving said rearward wobble plate and wherein said rearward wobble plate is defined as a first and a second semi-circular moon shaped member having flat forward and rearward surfaces at an angle to each other, said members removably supported to each other to form a plate having an axial opening therethrough, said opening of a size to freely receive said drive shaft, the forward surface of said plate adaptable for bearing engagement with the rearward face of said forward wobble plate and the rearward face thereof being formed at an angle re1ative to the forward face thereof, and each of said members having an integral guide portion extending from the opening forming boundary thereof, said guide portions extending in the nominal plane of said member, said guide portions extending within said slot in said drive shaft as said members are assembled about said shaft.

4. A multi-piston variable stroke pump power end according to, claim 2 wherein said drive shaft has an elongated slot extending therethrough at the area thereof receiving said rearward wobble plate and wherein said rearward wobble plate is defined as 7 8 a circular plate member having anopening therein References Cited by the Examiner freely receiving said shaft, the plate member having UNITED STATES PATENTS fiat forward and rearward surfaces disposed at an angle to each other, said plate member having a 2,968,961 1/1961 103*38 central opening therethrough perpendicular the nom- 5 3139037 6/1964 Budzlch 103 162 inal axis thereof; and FOREIGN PATENTS a rod member received by said opening in said mem- 139,982 1/1951 Australia bet and said slot of -in said shaft as said member is supported about said shaft. LAURENCE V. EFNER, Primary Examiner. 

1. A MULTI-PISTON VARIABLE STROKE PUMP POWER END COMPRISING IN COMBINATION: A HOUSING; A DRIVE SHAFT ROTATABLY SUPPORTED IN SAID HOUSING AND HAVING THE REARWARD END THEREOF EXTENDING FROM SAID HOUSING; A MULTIPLICITY OF PUSH RODS SLIDEABLY SUPPORTED IN SAID HOUSING ADJACENT THE FORWARD END OF SAID DRIVE SHAFT, EACH OF SAID PUSH RODS SUPPORTED PARALLEL THE AXIS OF SAID DRIVE SHAFT AND EACH DISPLACED AN EQUAL DISTANCE THEREFROM; A FORWARD WOBBLE PLATE SUPPORTED ON SAID DRIVE SHAFT, SAID FORWARD WOBBLE PLATE HAVING ENGAGEMENT AT THE FORWARD FACE THEREOF WITH THE REARWARD END OF EACH OF SAID PUSH RODS, SAID FORWARD WOBBLE PLATE FREE TO WOBBLE ON SAID DRIVE SHAFT; A REARWARD WOBBLE PLATE SUPPORTED ABOUT SAID SHAFT, THE FORWARD FACE THEREOF IN BEARING ENGAGEMENT WITH THE REARWARD FACE OF SAID FORWARD WOBBLE PLATE, THE REARWARD FACE OF SAID REARWARD WOBBLE PLATE BEING FORMED AT AN ANGLE RELATIVE TO THE FORWARD FACE THEREOF; A TUBULAR WOBBLE PLATE ADJUST MEMBER ROTATABLY AND AXIALLY SUPPORTED ABOUT SAID SHAFT, SAID WOBBLE PLATE ADJUST MEMBER HAVING A FLAT FORWARD FACE THEREOF INCLINED AT AN ANGLE TO THE AXIS OF SAID SHAFT, SAID FORWARD FACE THEREOF IN FRICTIONAL ENGAGEMENT WITH SAID REARWARD FACE OF SAID REARWARD WOBBLE PLATE, SAID WOBBLE PLATE ADJUST MEMBER HAVING A PORTION THEREOF EXTENDING COAXIALLY OF SAID SHAFT AND EXTERIORALLY OF SAID HOUSING; BEARING MEANS ROTATABLY SUPPORTING SAID WOBBLE PLATE ADJUST MEMBER TO SAID HOUSING; AND MEANS EXTERNALLY OF SAID HOUSING OF ADJUSTABLY SECURING SAID WOBBLE PLATE ADJUST MEMBER TO SAID SHAFT. 